There's a lot of frikkin people in the world. With that many rolls of the dice, the odds are in favor of stuff like this happening somewhere, eventually. And in the Internet age, we're gonna hear about it when it does!

The years just pass like trains. I wave, but they don't slow down.-- Steven Wilson

To me, the story is plausible in that the ring actually did not travel too far. It was believed to have been lost in a compost bucket near the kitchen sink, and would then have been either been fed to the sheep or worked into the vegetable row. So, 50/50 chance of being lost forever in the sheep pasture, versus being worked into the vegetable row for fertilizer. Assuming they work up and plant their garden vegetables in roughly the same place every year (my own folks certainly do), the odds were pretty good that it would eventually turn up on or near some sort of root vegetable, given enough repeated plantings (sixteen years, in this case).